1. Field of the Invention
The present invention relates to a moisture absorbing element for dehumidifying and drying in an apparatus designed to dehumidify and dry gas containing water vapor. More particularly, it relates to a moisture absorbing element that is excellent in moisture absorbing performance, capable of easily remove absorbed moisture at low temperature, and is reusable by regeneration.
2. Description of the Related Prior Art
When using a moisture absorbing material in dehumidifying and drying gas containing water vapor, elements carrying moisture absorbing material on the inner wall of plural gas passages are generally employed. A method of forming moisture absorbing elements is to shape into honeycomb structure having plural gas passages by laminating metal plates such as aluminum, paper sheets of inorganic fibers, or nonwoven fabrics, etc., and carrying, before or after this process, any substance selected from silica gel, synthetic zeolite, active carbon, deliquescent substance such as lithium chloride, and calcium chloride, as moisture absorbing material.
The moisture absorbing material used in the prior art is mainly silica gel, moisture absorption rate of which is 40 wt. % at most, while zeolite or active carbon is about 25 wt. % in moisture absorption rate. Herein, the moisture absorption rate refers to the rate of weight of absorbed moisture in a sample when moisture is absorbed at equilibrium at 20.degree. C., 65% RH to weight of the sample in complete dry state. It is necessary to use a binder to prepare moisture absorbing elements by impregnating these materials in elements, and therefore in such case the moisture absorption characteristic become low. To enhance the practical moisture absorption efficiency, at the present, the moisture absorbing elements must be increased in size.
To remove the moisture once absorbed in the moisture absorbing elements, there are various methods such that heated air is sent in, that heating wires are passed in the elements to heat them, etc. Hereinafter, this temperature is called the regeneration temperature. In the conventional moisture absorbing elements, when the regeneration time is about 30 minutes, the regeneration temperature is over 120.degree. C. This is because the releasing performance of the moisture adsorbed on the moisture absorbing elements is poor, and much regeneration air is needed when regenerating. And high temperature as such is not preferable from the viewpoint of energy. In particular, when deliquescent substances such as lithium chloride and calcium chloride are carried as moisture absorbing materials, the problems of high regeneration temperature and long regeneration time become more obvious. Moreover, when the regeneration temperature is high, it is not suited to use to dehumidify and dry in house from the aspects of safety and energy. For household use, the regeneration temperature should be 110.degree. C. or less, preferably 80.degree. C. or less. If the conventional moisture absorbing elements are regenerated at such temperature, it takes a very long time in regeneration, and the time used for dehumidifying and drying air as the intrinsic function of moisture absorbing elements is sacrificed.
Owing to such problems, moisture absorbing elements had been not used in household dehumidifiers. The conventional household dehumidifiers were of refrigerating type. Therefore drain produced must be discharged regularly, and the room space was occupied because of stationary type.
In this background, there was a demand for a dehumidifying and drying apparatus having a high moisture absorbing performance, capable of easily removing absorbed moisture at 110.degree. C. or less, which can be installed in the window, wall, floor, ceiling, etc., and does not produce drain to be discharged.